Lord Browne: Business genius who lost the Midas touch...

The reputation of BP, Britain's largest company, and its chief executive Lord Browne are inextricably woven together.

Now his character has been stained and the standing of the group tainted by scandal.

Browne was both the genius who turned a second-tier oil company into a global giant and the boss who clamped down on costs so hard that the group's hard-won efforts to present itself as "ethical," was destroyed by horrendous safety and environmental failings in Alaska and Texas.

Until now it was thought that the determination of BP's hard-bitten Irish chairman Peter Sutherland to force Browne from office this July, 18 months earlier than announced, was a response to the 2005 Texas City explosion, in which 15 people died and hundreds were injured.

Now we know differently.

In parallel with fighting for his future with a bitterly divided board, Browne was also battling on a personal front.

His combat was not just about keeping his relationship with his gay partner Jeff Chevalier secret - in an industry known for its macho, gung ho attitudes - but to prevent allegations of his misuse of BP facilities leaking into the public domain.

Once that became known, Browne had no choice but to immediately quit.

His resignation is extremely costly. He will have to forgo a year's notice entitlement of £3.5million as well as a controversial performance payment of £12million which would have been due this summer.

It was this latter payment which triggered an unusual shareholders revolt at last month's annual general meeting of BP at which more than 20 per cent of shareholders declined to approve his pay package.

He will nevertheless leave with shares and pension rights valued at £55million after a 42-year career.

It is a cardinal rule in the governance of public companies that there should be no intermingling of company affairs with personal business interests.

Any such conflicts have to be shared with directors and shareholders in the annual report.

Not only is he accused of flouting these rules, he has been branded as having lied to the court, breaking the old City code "my word is my bond."

Browne potentially placed the security of BP's operations and strategy at risk by allowing his boyfriend Chevalier access to a company computer containing critical corporate date.

But even more damagingly he used a senior executive, Dr David Christopher Allen, to assist his gay partner in setting up a mobile ringtone company, Txist.

Both Browne and Allen served on the board of a company rated as "high risk".

BP's board was initially reluctant to abandon Browne when a crisis in the American operations emerged in 2005. He was the man who created the modern BP.

When the oil price slumped at the end of the 1990s because of a meltdown in the Far East and a slump in the United States, John Browne saw an opportunity.

He made audacious takeover bids for two of America's oil majors Amoco, which dominated the Mid-Western United States, and Arco - the former Atlantic Richfield - which was all-powerful on the West Coast.

This, together with BP's domination of oil exploration on Alaska's North Slope, allowed it to become a giant which challenged Exxon and its main European rival Royal Dutch Shell for global hegemony.

Not just satisfied with securing the American market place, BP concluded a landmark partnership deal in Russia giving it access through the TNK-BP partnership to one of the most valuable oilfields in the world.

When Browne presented bumper results to the world a year ago he was able to make the astonishing and true claim that one pound in every six paid into pension funds and insurance companies in Britain, came from investments in BP.

Moreover, it was also the nation's biggest taxpayer helping to support the public services and the New Labour administration with which he was intimately involved.

Since the high point of early 2006 Browne's world has come tumbling down around him.

Relentless investigations into the Texas City explosion uncovered the unpleasant truth that ruthless cost-cutting, directed by Browne and minions, were partly responsible for the safety lapses.

As if this were not enough, parallel criminal inquiries in Alaska found that BP had been negligent in repairing pipelines carrying oil across the Arctic wilderness.

Browne was so powerful that he managed to negotiate an extension to his contract as chief executive which would yield huge new share options and keep him in power to the end of 2008.

But on the BP board, a power struggle was developing, with the chairman Sutherland pushing for an earlier departure and the naming of Browne's replacement, Tony Hayward.

As a result of the ensuing uproar, Browne had agreed to leave office this summer.

Any hopes he had of a glorious departure and a future life advising governments and collecting non-executive directorships are now all but ruined.

Hayward, his young and untested successor now faces formidable challenges in running the £100billion-plus company.

BP is still deeply embroiled in investigations in Texas, Alaska and New York.

He will have to battle with Putin over the future of BP's Siberian oilfields at a time when the Russians are seeking to grab back foreign ownership.

Most importantly, he will need to rebuild the company's ethical reputation which has been severely dented by the tumultuous events in the Royal Courts of Justice.